Effect of Loop Diuretics on the Fractional Excretion of Urea in Decompensated Heart Failure

BACKGROUND

Fractional excretion of urea (FEUrea) is often used to understand the etiology of acute kidney injury (AKI) in patients receiving diuretics. Although FEUrea demonstrates diagnostic superiority over fractional excretion of sodium (FENa), clinicians often assume FEUrea is not affected by diuretics.

OBJECTIVE

To assess the intravenous loop diuretic effect on FEUrea.

METHODS

We analyzed a prospective cohort (n=297) hospitalized with hypervolemic heart failure at Yale New Haven Hospital System. FENa and FEUrea were calculated at baseline and serially after diuretics. The change in FEUrea at peak diuresis was compared with the pre-diuretic baseline.

RESULTS

Mean baseline FEUrea was 35.2% ± 10.5% and increased by a mean 5.6% ± 10.5% following 80 mg (40-160 mg) of furosemide equivalents (P < .001). The magnitude of change in FEUrea was clinically important as the distribution of change in FEUrea was similar to the overall distribution of baseline FEUrea. Change in FEUrea was related to the diuretic response (r = 0.61, P < .001), with a larger FEUrea increase in diuretic responders (8.8%, interquartile range [IQR]: 1.8-16.9) than non-responders (1.2%, IQR: -3.2 to 5.5; P < .001). Diuretic administration reclassified 27% of patients between low and high FEUrea groups across a 35% threshold. Neither change in FEUrea nor percentage reclassified out of a low FEUrea category differed between patients with and without AKI (P > .63 for both).

CONCLUSIONS

FEUrea is meaningfully affected by loop diuretics. The degree of change in FEUrea is highly variable between patients and commonly of a magnitude that could reclassify across categories of FEUrea.

Multiple audience problem: A strategic communication perspective on social perception

Examined how communicators send mixed messages containing an explicit surface content and a covert hidden content. In Study 1, Ss wrote constrained essays presenting either an introverted or extraverted personality. Although authors reported manipulating essay credibility and readers reported relying on credibility to make their judgments, readers succumbed to correspondence bias. In Studies 2 and 3, Ss again prepared either constrained essays (Study 2) or constrained videotapes (Study 3) and included in them a hidden message that would be understood by only their friends but not by strangers. Observers then read these essays or watched these videotapes. Friends detected and decoded the hidden messages, whereas strangers did not. We discuss these findings in terms of social perception and strategic communication.

Perceiving choice and constraint: The effects of contextual and behavioral cues on attitude attribution

We examined how features of the situation and the target's behavior in the attitude-attribution paradigm may lead observers to infer that the behavior was performed purposefully and how these perceptions may contribute to correspondence bias. Experiment 1 demonstrated that cues suggesting that essay assignment resulted from the target's purposeful action lead to correspondent inferences. When these cues were absent, observers' inferences were not correspondent. Experiment 2 demonstrated that observers are sensitive to cues emitted by the target (facial expressions of delight and disappointment) and that those cues' meaning depends on the context in which they take place. When the essay was freely chosen, the expression had little effect; observers judged that the essay accurately reflected the target's attitudes. When the essay assignment was constrained, observers used the expressions to discount the essay when judging the target's attitudes. We discuss the implications of these findings for the study of correspondent inferences and correspondence bias.

The assessment of permanent disability following injury to the hand

Each year approximately 290,000 workmen are injured on duty, 24,000 of whom will suffer some permanent disability and will merit financial compensation for their injuries. An accurate doctor's report is the single most important factor in ensuring that a workman receives fair compensation.

Pattern-reversal visual evoked potential in a case of nitrous oxide abuse and recovery

Pattern reversal visual evoked potentials were recorded in a dentist who had abused nitrous oxide while he showed neurologic impairment and during recovery. The latency of the major positive peak (P100) remained constant during both phases. However, the amplitude of this peak was markedly reduced during the stage of neurologic involvement, and increased during recovery after withdrawal. The clinical significance of this is discussed.